4.9.3
Solar Control
4.10
EXCHANGING A BOILER
Before removing an existing boiler add Fernox Supafloc, or equivalent cleaning agent, in
accordance with the manufacturers instructions. Open all radiator valves and fire the
boiler. When the system is fully heated, shut off the gas supply and drain down the central
heating system.
Important
The Qudos 28h and Qudos 28hP condensing boilers contain components which could be
damaged or blocked by grease, dirt or solder etc. It is essential that sludge or scale is
removed from an existing system before fitting the boiler.
The guarantee provided with the Keston Qudos 28h and Qudos 28hP does not cover
damage caused by system debris or sludge.
Connect the new boiler as instructed in this manual and fit in accordance with Sections
4.1 to 4.8
Fill to a pressure of about 2.5 bar, if on a sealed system. Check the complete system for
water soundness. If leaks need to be rectified using flux or solder the system must be
flushed cold again before proceeding.
Reduce the pressure to the Initial System Design Pressure, if on a sealed system. Vent
the system.
Gas Supply
The complete gas installation up to the boiler gas control valve must be checked for
soundness. BS 6891.
Electrical Installation
Carry out preliminary electrical safety checks, i.e. Earth continuity, Polarity, Resistance to
Earth, Short Circuit and earth loop impedance using a suitable test meter.
Initial Firing
The gas pressure setting is factory adjusted to within the required range and does
not need readjustment.
If the reading is incorrect then check such factors as tightness
of the air and flue pipe joints, pressure sensible joints and the gas inlet pressure
WD440/3/2007
Chapter 4 : Installation
The Keston Qudos 28h & Qudos 28hP Boilers
Installation & Servicing Instructions
Page : 25
S
Y
S
T
E
M
P
U
M
P
SYSTEM PUMP
E
N
L
THERM
OPEN
EXTERNAL SENSOR
( OPTIONAL )
SENSOR
SOLAR PANEL
SOLAR PANEL
TS SENSOR
TANK
DHW SENSOR
SOLAR CONTROL WITH DHW SENSOR INPUT
CONTROLS
FROM DHW
CONTROLS
FROM CH
GREY
ORANGE
BROWN
BLUE
M
VALVE
DHW ZONE
VALVE
CH ZONE
BROWN
GREY
BLUE
ORANGE
M
(
3
A
F
U
S
E
)
2
3
0
V
M
A
IN
S
U
P
P
L
Y
E
N
L
BOILER
M
A
IN
C
O
N
N
E
C
T
O
R
LOW VOLTAGE CONNECTOR
Q28H
E
PUMP
SWITCH
C
2
1
CH1
1
0-1
0V
0v
2
SENSOR
1
2
SENSOR
2
SENSOR
1
1
2
NO
SOLAR
SOL.
DHW
TS
FLOW
ANALOG
DEMAND
EXTERNAL
SENSOR
M
A
IN
S
U
P
P
L
Y
S
O
L
A
R
P
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P
C
H
D
E
M
A
N
D
1
N
N
S
L
1
S
L
2
E
L
L
O
C
K
O
U
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C
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N
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2
C.10C.0.09.00.0
